1. Field of the Invention
This invention relates to a puffer type gas circuit breaker and, more particularly, the invention relates to a puffer type gas circuit breaker of a large capacity in which a pair of circuit breaking units are connected in series with each other.
2. Description of the Prior Art
A puffer type gas circuit breaker has a simple structure and it is advantageous in that since a low pressure can be adopted for SF.sub.6 gas to be used as the insulating medium, the SF.sub.6 gas does not become liquefied. However, it is defective in that when a large current such as exceeding 50 KA is broken, a very high operating force is required. The capacity of power-transmission lines has recently been increased with an increase in the demand for electric power, and the intensity of electric current to be broken by the breaker also increases. Accordingly, the operating force for operating the puffer type gas circuit breaker has to be increased. As a means for solving this problem, there has to been developed a puffer type gas circuit breaker in which an electromagnetic force is produced by a breaking current flowing in breaking units and this electromagnetic force is utilized as the operating force. In these conventional puffer type gas circuit breakers utilizing an electromagnetic force as the operating force, an electromagnetic actuating unit is mounted for each of the breaking units, respectively, and therefore, the structure is complicated.
As a means for overcoming this disadvantage, there has been proposed a circuit breaker in which a conventional puffer type gas circuit breaker unit of a simple structure is utilized for each of at least 2 breaker units having breaker points and an electromagnetic actuating device is disposed from the outside in the middle of the operating mechanism (see copending U.S. application Serial No. 520,906, filed November 4, 1974, and assigned to the assignee of the present application.) In this previous proposal, however, since the current transferring means for applying an electric current to the electromagnetic actuating device is arranged at a part where the electromagnetic actuating device is disposed, there is brought about a defect that the structure of the electromagnetic actuating device has to be complicated to some extent.